Dance on Thatcher's grave, but remember there has been a coup in Britain

In the wake of Thatcher's departure, I remember her victims. Patrick Warby's daughter, Marie, was one of them. Marie, aged five, suffered from a bowel deformity and needed a special diet. Without it, the pain was excruciating. Her father was a Durham miner and had used all his savings. It was winter 1985, the Great Strike was almost a year old and the family was destitute. Although her eligibility was not disputed, Marie was denied help by the Department of Social Security. Later, I obtained records of the case that showed Marie had been turned down because her father was "affected by a Trade dispute".

The corruption and inhumanity under Thatcher knew no borders. When she came to power in 1979, Thatcher demanded a total ban on exports of milk to Vietnam. The American invasion had left a third of Vietnamese children malnourished.

I witnessed many distressing sights, including infants going blind from a lack of vitamins. "I cannot tolerate this," said an anguished doctor in a Saigon paediatric hospital, as we looked at a dying boy. Oxfam and Save the Children had made clear to the British government the gravity of the emergency. An embargo led by the US had forced up the local price of a kilo of milk up to ten times that of a kilo of meat. Many children could have been restored with milk. Thatcher's ban held.

In neighbouring Cambodia, Thatcher left a trail of blood, secretly. In 1980, she demanded that the defunct Pol Pot regime – the killers of 1.7 million people – retain its "right" to represent their victims at the UN. Her policy was vengeance on Cambodia's liberator, Vietnam. The British representative was instructed to vote with Pol Pot at the World Health Organisation, thereby preventing it from providing help to where it was needed more than anywhere on earth.

To conceal this outrage, the US, Britain and China, Pol Pot's main backer, invented a "resistance coalition" dominated by Pol Pot's Khmer Rouge forces and supplied by the CIA at bases along the Thai border. There was a hitch. In the wake of the Irangate arms-for-hostages debacle, the US Congress had banned clandestine foreign adventures. "In one of those deals the two of them liked to make," a senior Whitehall official told the Sunday Telegraph, "President Reagan put it to Thatcher that the SAS should take over the Cambodia show. She readily agreed."

In 1983, Thatcher sent the SAS to train the "coalition" in its own distinctive brand of terrorism. Seven-man SAS teams arrived from Hong Kong, and British soldiers set about training "resistance fighters" in laying minefields in a country devastated by genocide and the world's highest rate of death and injury as a result of landmines.

I reported this at the time, and more than 16,000 people wrote to Thatcher in protest. "I confirm," she replied to opposition leader Neil Kinnock, "that there is no British government involvement of any kind in training, equipping or co-operating with the Khmer Rouge or those allied to them." The lie was breathtaking. In 1991, the government of John Major admitted to parliament that the SAS had indeed trained the "coalition". "We liked the British," a Khmer Rouge fighter later told me. "They were very good at teaching us to set booby traps. Unsuspecting people, like children in paddy fields, were the main victims."

When the journalists and producers of ITV's landmark documentary, Death on the Rock, exposed how the SAS had run Thatcher's other death squads in Ireland and Gibraltar, they were hounded by Rupert Murdoch's "journalists", then cowering behind the razor wire at Wapping. Although exonerated, Thames TV lost its ITV franchise.

In 1982, the Argentine cruiser, General Belgrano, was steaming outside the Falklands exclusion zone. The ship offered no threat, yet Thatcher gave orders for it to be sunk. Her victims were 323 sailors, including conscripted teenagers. The crime had a certain logic. Among Thatcher's closest allies were mass murderers – Pinochet in Chile, Suharto in Indonesia, responsible for "many more than one million deaths" (Amnesty International). Although the British state had long armed the world's leading tyrannies, it was Thatcher who brought a crusading zeal to the deals, talking up the finer points of fighter aircraft engines, hard-bargaining with bribe-demanding Saudi princes. I filmed her at an arms fair, stroking a gleaming missile. "I'll have one of those!" she said.

In his arms-to-Iraq enquiry, Lord Richard Scott heard evidence that an entire tier of the Thatcher government, from senior civil servants to ministers, had lied and broken the law in selling weapons to Saddam Hussein. These were her "boys". Thumb through old copies of the Baghdad Observer, and there are pictures of her boys, mostly cabinet ministers, on the front page sitting with Saddam on his famous white couch. There is Douglas Hurd and there is a grinning David Mellor, also of the Foreign Office, around the time his host was ordering the gassing of 5,000 Kurds. Following this atrocity, the Thatcher government doubled trade credits to Saddam.

Perhaps it is too easy to dance on her grave. Her funeral was a propaganda stunt, fit for a dictator: an absurd show of militarism, as if a coup had taken place. And it has. "Her real triumph", said another of her boys, Geoffrey Howe, a Thatcher minister, "was to have transformed not just one party but two, so that when Labour did eventually return, the great bulk of Thatcherism was accepted as irreversible."

In 1997, Thatcher was the first former prime minister to visit Tony Blair after he entered Downing Street. There is a photo of them, joined in rictus: the budding war criminal with his mentor. When Ed Milliband, in his unctuous "tribute", caricatured Thatcher as a "brave" feminist hero whose achievements he personally "honoured", you knew the old killer had not died at all.